Traditional engine systems include an engine with an air intake manifold. Air flows into the intake manifold through an air inlet. An air filter filters the inlet air to remove dirt or debris. A mass air flow (MAF) sensor measures or estimates the mass of air flowing through the air inlet into the engine. The controller determines an appropriate A/F ratio for engine operation based on the MAF. A driver adjusts a throttle valve using an accelerator pedal to regulate the air flowing into the intake manifold.
Reversion is the reverse flow of engine air from the intake manifold back through the air inlet. Conventional MAF sensors are unable to detect reversion, and therefore overstate air flow during reversion. The error adversely impacts engine control. More specifically, the air expelled from the engine during reversion is measured by the MAF sensor as intake air because the sensor is unable to detect when reversion occurs. As a result, it is possible for a mass of air to be measured multiple times by the MAF sensor. The error leads to higher MAF estimates than actually exist.